SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c34cd56aad7811128f4e630bbf52cffc309babfed401f53abd2a202651abf246' 
  AND token = '3O1zB+d5TMbvccQEfrsrbOYLYYzEHbURMAjION3gBOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}